/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification
 *             of Java bytecode.
 *
 * Copyright (c) 2002-2020 Guardsquare NV
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.obfuscate;

import proguard.classfile.Clazz;

/**
 * NameFactory which only generates names that don't exist yet as members on the class for which it
 * is created.
 *
 * @author Johan Leys
 */
public class UniqueMemberNameFactory implements NameFactory {
  private static final String INJECTED_MEMBER_PREFIX = "$$";

  private final NameFactory delegateNameFactory;
  private final Clazz clazz;

  /**
   * Utility for creating a new NameFactory that can generate names for injected members: the
   * generated names are unique within the given class, and don't clash with non-injected members of
   * its super classes.
   *
   * @param clazz The class for which to generate a NameFactory.
   * @return The new NameFactory instance.
   */
  public static UniqueMemberNameFactory newInjectedMemberNameFactory(Clazz clazz) {
    return new UniqueMemberNameFactory(
        new PrefixingNameFactory(new SimpleNameFactory(), INJECTED_MEMBER_PREFIX), clazz);
  }

  /**
   * Creates a new UniqueMemberNameFactory.
   *
   * @param delegateNameFactory The delegate NameFactory, used for generating new candidate names.
   * @param clazz The class in which to check for existing member names.
   */
  public UniqueMemberNameFactory(NameFactory delegateNameFactory, Clazz clazz) {
    this.delegateNameFactory = delegateNameFactory;
    this.clazz = clazz;
  }

  // Implementations for NameFactory.

  public String nextName() {
    String name;

    // Check if the name doesn't exist yet. We don't have additional
    // descriptor information, so we can only search on the name.
    do {
      name = delegateNameFactory.nextName();
    } while (clazz.findField(name, null) != null || clazz.findMethod(name, null) != null);

    return name;
  }

  public void reset() {
    delegateNameFactory.reset();
  }
}
